Monday, 12 February 2018

Dewalt DW738 Bandsaw Review

I've had this bandsaw now for nearly 10 years and thought it's about time to review it.
Essentially this is a 13" bandsaw (nominally 12") and has a resaw capacity of 155 mm or 6".
The version I have is a 2 speed saw with the speed changed by moving the drive belt onto different pulleys. When supplied from the factory it is in low speed mode and I didn't move that setting until early on in 2014. Then it was found that it ran much too fast for the type of work I use it for. So I moved it back to the slow speed. It is more trouble than it is worth to change it.
Assembled Dewalt DW738 Bandsaw

There is another saw with a continuously adjustable speed setting and it is designated the DW739. That saw is not reviewed here but probably is similar in specification and operation.

Unlike a lot of good Dewalt equipment it should be a different colour. Like Bosch DIY green against Pro blue. Dewalt DIY stuff needs to be brown instead of corporate professional yellow. It is definitely hobby DIY level but has served me well for the last 10 years.



Features.

  • Aluminium fence clamped at both ends
  • Table moves 45 degrees one way and about 2 degrees the other.
  • High quality, rigid, cast aluminium construction suitable for wood, non-ferrous metal, foam, composites and plastics applications
  • Large balanced aluminium band wheels with rubber linings
  • 50mm Dust extraction port
  • Micro switch incorporated in the door to prevent accidental starting while open
Specification lifted from Dewalt website:

  • Power Input 749 Watts
  • Power Output 550 Watt
  • Max. Cutting Height 155 mm
  • Max. Cutting Width 310 mm
  • Cutting Speed 330/800 m/min
  • Table Size 380 x 380 mm
  • Weight 23.0 kg
  • Depth 520 mm
  • Length 660 mm
  • Height 1000 mm
  • Sound Power 105 dB(A)
  • Sound Power Uncertainty 4.0 dB(A)
  • Sound Pressure 92.0 dB(A)
  • Sound Pressure Uncertainty 3.3 dB(A)

Accessories

Hex keys - various
Open tube wrench

Options

I bought the optional stand for the saw but find for me it is not high enough. So I have it mounted onto a shop made timber pallet mounted within a mobile base. This brings it up to a comfortable operating position.
I also bought the optional adjustable mitre gauge that runs in the standard slot on the table.

Blades

6mm to 16mm wide and length is 2095mm or 82.5" and are readily available from various retailers.
The saw as supplied will cut wood but will also cut plastic and non ferrous metal with the appropriate blade. A 16mm blade will put the frame under considerable stress. I have a 16mm blade and had to crank down on the tensioner a long way and even then it would not run satisfactorily. Resaws are definitely not easily done with this blade as it cannot be tensioned high enough.

No such issues with a 12mm blade as that is lower tension. So I recommend only going to the larger size occasionally.
I mostly keep a 6mm blade on the machine and keep it at the correct tension which does not stress the frame.

Adjustment.

As can be expected with a bandsaw there are many adjustments available to tune the saw to the blade being used. 
  • The rear of blade bearing is a thrust ball bearing of high quality.
  • The tensioning mechanism is a plastic hand wheel attached to a very long threaded rod running into the machine. There is a table on the side of the blade guard that shows how the blade tension should be for each width of blade. As usual this is no more use than ornament and I resort to the sideways deflection of each blade to judge the correct (ish) tension.
Upper tension spring

  • Centralization screw. There is a screw to adjust the angle of the top wheel to alter the blade position on the crowned, banded edge of the wheel. This again is reasonable quality.
  • A rack and pinion mechanism moves the upper bearing assembly up or down. This can give the appearance of too much play. There is a nyloc nut that can be adjusted to minimise slop but not totally eliminate it.

Construction

  • The saw is cast in what appears to by aluminium alloy and has several strengthening webs/ribs cast in to aid strength when under higher tensions. All appears to have been well designed and functional. The access door to the blade is made from a high impact black plastic with captive bolts to tighten up when the door is shut. There is also a push in manual interlock piece that automatically ejects if you attempt to open the door. A good safety feature. As the latch is fixed to the door with a short length of plastic chain it is not easy to override the interlock and power the machine without the guard being in place.
Internal components

  • The table is made from aluminium alloy and is coated with a non stick surface (probably PTFE) and is of robust construction. There is a slot to enable blade changes. There is also a strange catch that is supposed to lock both halves of the split together. I think it is also intended to align both halves of the split but in practice I find it puts them in different planes. I leave that latch in the unlatched position and the halves are perfectly aligned.
Cast aluminium table


Underside of table


  • The upper blade support is mounted on a rack and pinion adjustable bracket that appears a little flimsy. 
Upper Blade Support

  • The side bearings are metal rubbing blocks held in their respective carriers with the use of a hex headed grub screw. As mentioned the rear bearings are real thrust ball bearings and can be adjusted fore and aft.
Rubbing blocks. The good point is that these are very cheap to replace when worn. There is no kit to convert these to bearings though

  • The blade support principal is repeated on the lower blade guide.
  • The motor is a powerful but very quiet induction motor and seems to be very high quality.
  • The interlocked on off switch is of the NVR type. For instance during a cut if the external power is lost and comes back on the switch will not restart the motor until the green button is pressed again.
  • The weight of the saw without leg-stand is 23KG and doesn't sound like a lot. However when mounted onto the leg-stand and that in turn bolted down the saw is going no where.

Blade changing

This is the only part of the saw that is a bit of a chore to do. If you have broken a 1/4" blade and need to replace it with a new one then that is a simply task. However if you want to change the blade to anything bigger than 1/4" then is becomes a bit more complicated. The manual states you can change a blade without removing anything. In practice that is true of the 1/4" blade. When it gets any wider I found it is far easier to just remove the table and replace the blade. There not enough room around the throat area to rotate the blade enough to thread it through into the sliding blade guard on the blade support mechanism.
Once that is done adjustment of the cool blocks and the rear bearing is relatively simple.

Operation.

It is easy to adjust the fence to desired thickness. The fence has two clamps one on the front and one on the rear. You have to tighten both and there are markings on the table at the front in mm. There are also shallow slots cast into the table that run from front to rear to enable you to judge whether the fence is parallel to the mitre slot and blade.
The fence is a little too low to enable resawing but you could always clamp an auxiliary fence onto it or a single point fence.
With a new blade it is possible to get very smooth cuts indeed on thin or thick stock. The blade does not bog down very easily so keeping gentle pressure on the work-piece enables efficient cutting. 
The supplied table blade insert is made from plastic and is adequate. I soon changed it for a shop made plywood zero clearance insert. The thickness of the insert is around 6mm so standard 6mm plywood or MDF works ok.

Shop made plywood insert in the aluminium table

Wider blades.

I think the 16mm blade is a little optimistic for this size of machine as you really need to get high tensions going to avoid wander. I did buy a 14mm blade and use that for a while but now limit myself to 6mm and 12mm blades only.

Resawing

I have successfully resawn boards to around 125mm (5") wide. To do this I have used either a 1/2" or 9/16" new blade. Also I have used a feather board in the standard 3/4" wide T slot. The results can be variable but as long as you make enough allowance you can book match panels. The thinnest that I have gone is around 10mm on 125 mm thick stock. Obviously this machine is not going to perform like a true resawing bandsaw and it isn't intended to be such a machine. It is OK for occasional resawing with a new blade.

Cut alignment.

It is possible to adjust this particular machine so you get no drift at all on a cut. I have achieved this several times using blades from Axminster. The blade running right on top of the crown of the wheel made this possible and also well aligned welds on the blades.

Tyre longevity

I still have the same original tyres fitted to both of my wheels and although there is considerable wear they still seem to function OK. I've run many thousands of linear feet of stock through this saw. It doesn't appear to be possible to replace the tyres on this bandsaw but spare upper and lower wheels are available for purchase.

Badly worn upper wheel tyre


Dust collection

2" extractor port
Now comes the dreaded dust collection. There is a 2" port fitted to the body casting below the cut. I attach a regular 50mm flex hose to this that is connected to my shop vac through a Dust Deputy. The shop vac has more than adequate suction but there are so many crevices inside and so many air leaks dust collection is dire. There is also the useful addition of a brush on the lower wheel wiping off dust.
Brush on lower wheel



The good points


  •  It uses an induction motor and operation is very quiet. 
  •  It tracks very well with a 1/4" blade.
  •  It has an optional leg stand that I bought but put it onto a mobile base and it is now at the ideal height
  •  It is very lightweight
  •  It cuts remarkably well with a new narrow blade (no more than 3/8")
  •  You can also cut non ferrous metals with the right blade. Also see respective bad point!

The bad points 


  •  It is very lightweight (a benefit and a disadvantage simultaneously)
  •  It bogs down if you go too thick or don't get the right feed rate. 
  •  It is also two speed but you have to change a belt on a pulley and it is more trouble than it is worth.
  •  It has a crappy cast aluminum table which is too light.
  •  It also has a non adjustable aluminum fence that isn't very high.
  •  Dust extraction is dire. There are loads of crevices inside for dust to get stuck even though I use a reasonable shop vac on it (It only has a 2" port so can't connect it to the large dust extractor)
  • Widest blade is 5/8" but the wheels are only about 3/4" wide so you can't set the blade as per that bandsaw TWW episode (gullet on the centre line).
  •  You can resaw up to about 6" stock with 1/2" to 5/8" blades but be prepared for barrel cuts. You can't get enough tension into the blade. 
  •  If cutting metal be prepared to strip the machine down to clean out the crap metal particles afterwards. Brass embeds really easy into the rubber drive wheel :( - don't ask!


I used that setup method that was on a recent TWW bandsaw setup episode (can't remember the guy who did it but he is big on the woodshow demonstration circuit) having also seen a similar method on 360 woodworking.

Conclusion

For a small hobby shop like mine this bandsaw has been a boon. I have been using it day in day out for nearly 10 years and have gone through numerous blades. It is good value for money and I think mine will be around for quite some time yet.
The saw is no longer current (February 2018) on Dewalt's website but you may be able to pick up one secondhand.

There are much better saws on the market now so unless you see one cheap get something else.

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